Determination of the minimum chip thickness and the effect of the plowing depth on the residual stress field in micro-cutting of 18 Ni maraging steel

Due to the cutting-edge radius effect in micro-cutting, there exists some material sticking in front of the cutting-edge named stagnation zone, above which the material flows as chips. The location of the stagnation zone is reported to be associated with the minimum chip thickness in micro-cutting, which is a significant value influencing the cutting mechanics and the machined surface integrity in micro-cutting. The determination of the minimum chip thickness is of great importance in micro-cutting process. In this paper, the cutting force analysis on the shearing plane was carried out considering the ductile fracture and cutting-edge radius. Based on the cutting force analysis, this paper proposed a new method to determine the minimum chip thickness in micro-cutting of 18Ni maraging steel through finite element simulation. The minimum chip thickness was calculated to be 0.25 times the cutting-edge radius, which is in a good agreement with the velocity distribution analysis of the material around the cutting-edge. In addition, the effect of the plowing depth which was equivalent to the height of the stagnation zone on the residual stress filed was investigated using energy criterion. The energy stored in the machined surface increased with the plowing depth, resulting from the increasing thermal-mechanical load due to plowing.